This invention relates to method of controlling bulk in folded webs and, more particularly, to the control of a folder line producing embossed interfolded webs.
Representative of a folder useful in the practice of this invention is that seen in co-owned U.S. Pat. No. 4,824,426. These are normally employed for towels, facial tissue, etc. Problems frequently arise in the folding back pressure at the folder outlet which results in improperly finished stacks. Although efforts have been made in the past to control stack back pressure by the operators --as by adjusting the nip in the embossing rolls --this has not proved successful because of the constant attention required to compensate for changes in web characteristics.
According to the invention, we overcome this drawback by sensinq the bulk of a bolt or stack issuing from the folder, forming a signal corresponding to the bulk of the bolt sensed, comparing the signal with a predetermined signal range and changing the nip gap or pressure in the embossing rolls whenever the signal is outside of the predetermined range.
Other objects and advantages of the invention may be seen in the details of the ensuing specification.